Signal responsive driving or follow-up device



Nov. 17, 1953 K. EZR 2,659,847

SIGNAL RESPONSIVE DRIVING OR FOLLOW-UP DEVICE Filed June 26, 1952 3Sheets-Sheet 1 I] II Zit 1 L H61 l INVENTOR Nov. 17, 1953 K. EZR

SIGNAL RESPONSIVE DRIVING OR FOLLOW-UP DEVICE Filed June 26, 1952IMPULSE GENERATOR FIG. 5

3 Sheets-Sheet 2 INVENTOR lurmzi '1.

Nov. 17, 1953 K. EZR 2,659,847

SIGNAL RESPONSIVE DRIVING OR FOLLOW-UP DEVICE Filed June 26, 1952 3Sheets-Sheet 3 46 II I: 97 I 5 AflPl/F/f/f cows/270R AND ACAHPLlf/ER 5 6IMPULSE GENERATOR INVENTOR Mam]. L

Patented Nov. 17, 1953 UNITED STATES SIGNAL RESPONSIVE DRIVING RFOLLOW-UP DEVICE Karel Ezr, Prague, Czechoslovakia, assignorto Tesla,Narodni Podnik, Prague, Czechoslovakia, a corporation of CzechoslovakiaApplication June 26, 1952, Serial No. 295,801

16' Claims.

This invention relates to signal responsive drivin or follow-up devicesand, more particularly, to a reversible follow-up mechanism or deviceproviding a relatively large magnitude operating force proportional to arelatively small magnitude signal and operating in a directiondetermined by the sense of the signal.

Devices of the type to which the invention relates are designed toproduce predetermined linear, rotary or other movement of a controlleddevice, such as an actuator or a recorder, responsive to a controlsignal. They are frequently used in remote control operating orrecording systems.

For best results, the devices-should be readily responsive to changes inindicated operating direction, rugged, simple, and operable on a lowpower input, while being capable of providing a sumciently largeoperating force to assure posi tive movement of the controlled apparatusresponsive to the controlling impulse or signal.

In accordance with the present invention, a novel, simple and efficientfollow-up mechanism is provided which fulfills the foregoingrequirements completely. More specifically, the invention comprises areciprocable or oscillatable member or operator with which isfrictionally associated a movable follow-up element having anappreciable moment of inertia. The friction between the operator and thefollower is independent of the speed of the movement of the contactfaces of the operator and the follower, that is to say, the absolutevalue of the force which aifects the follower due to this friction isconstant even if the speed of the movement of the operator is variable.Means are provided to reciprocate or oscillate the operator in such amanner that it is given a quick sharp movement in a direction oppositeto the de sired movement of the follower and returns in the otherdirection at a slower steadier space. In both directions of thisasymmetrical movement of the operator, the force due to friction betweenthe operator and the follower is the same. But in the direction of thequicker movement of the operator, this force acts on the follower duringa shorter period than during the slower movement in the oppositedirection. Thus the resuiting movement of the follower is in thedirection of the slower movement of the operator. It is also possible toadjust the friction between the follower and the operator so that duringthe quicker movement of the operator the follower does not move with theoperator, whereas in the direction of the slower movement it is draggedalong with the operator.

The impulses imparted to the operator have a constant frequency and anamplitude and shape corresponding to the controlling signal. Preferably,the impulses are applied magnetically to the operator, withelectromagnetic operators being energized with discrete power pulses. Toprovide the required impulse strength from relatively weak signals, anelectronic amplifier may be employed in circuit between the signalsource and the electromagnetic dynamic system.

Due to the operator being a relatively light, low inertia element ascompared to the follower, only a relatively small power input isrequired as compared to systems in which impulses are imparted to arelatively heavy operator associated with a relatively light follower.In the invention system, the actual movement of the follower is eifectedby the springs acting to return the operator to the neutral position,and the power required is only that necessary to move the operatoralone.

For an understanding of the invention principles; reference is made tothe following description of typical embodiments thereof as illustratedin the accompanying drawings. In the drawings:

Fig. 1 is a somewhat schematic plan view of a dynamic system embodyingthe invention;

Figs. 2 and 3 illustrate types of'electrical pulses which may beutilized to operate the system;

Fig. 4 is a schematic circuit diagram of one form of electronic operatorfor the dynamic system;

Fig. 5 is a schematic diagram of a measuring or recording systemembodying the invention;

Fig. 6 is a schematic wiring diagram of another form of electronicoperator for the system;

Fig. '7 is a schematic diagram of another form of measuring or recordingsystem embodying the invention; and

Figs. 8 and 9 illustrate the invention dynamic system as applied toobtain a rotary follow-up movement.

Referring to Fig. 1, the dynamic system is illustrated as including arelatively low inertia operator or driver in the form of a rod i. Thisrod is suspended at its ends on a pair of resilient restoring strips 3and in such a manner that rod i may reciprocate parallel to its length.

The follower or driven element comprises a relatively higher inertiamember 2 which is slidable along the rod l and has frictional engagementthereto.

The relative of driver I and follower 2 are so selected that, if rodmoves quickly in one aesasm direction, follower 2 remains practicallystationary, with rod I sliding through the follower. When rod I isreturned more slowly in the opposite direction, it carries follower 2along with it due to friction between the rod and follower. If thefriction between the rod and the follower is adjusted in such a mannerthat the follower is dragged along with the operator in both direc tionsof the movement thereof, the resulting movement of the follower is inthe direction oi the slower movement of the operator, as explainedabove.

The operation of this dynamic system depends on the ratio of thefrequency of the exciting impulses and the natural mechanical frequencyoi the dynamic system, the shape 2nd magnitude of oscillation of thedriver, the relative masses of the driver I and follower 2, and thefriction between the driver and follower. If these parameters areproperly selected, an efficient, low power consumption, and sensitivelyresponsive dynamic system is provided.

Rod I may be reciprocated or oscillated by electromagnets 5 and 6 actingupon paramagnetic end pieces 1 and 8 on the rod I. The electric currentimpulses for exciting the electromagnets 5 and 5 may be fed to either orboth electromagnets. However, if both electromagnets are excited withpulses of the same frequency and amplitude, having a phase difference of180, there will be no net movement of follower 2 as rod I would move inboth directions at the same speed. Hence. means must be provided to dscriminately energize the electronic gnets in such manner as to produceunequal movements of rod I in opposed directions.

For example, the electromagnets may be ener gized with saw tooth pulsessuch as shown in Fig. 2. A simpler way to effect an asymmetrical.movement of rod I is to utilize the periodic pulses or pulsating currentshown in Fig. 3 which are used to energize the dynamic systems whosenatural mechanical frequency differs from the frequency of the excitingpulses of Fig. 3. These pulses are fed to only a selected one of theelectromagnets 5, 6 in accordance with the sense of the controllingsignal. The wave form of Fig. 3 can be produ ed readily by rectifyingsinusoidal alternating current.

To provide suificient power for the electromagnets, as well as toprovide control of the direct on and amount of movement of follower 2,an electronic control system is employed in preference to relays, as thelatter are sub ect to malfunctioning due to contact deteriorrtion. Inone form of circuit as shown in Fig. 4, the wind ngs 9, II! ofelectromagnets 5, '5 are included in the anode circuits of electronicvalves, such as triodes II, I2 having substantially identical operatingcharac teristics and whose anode circuits are supplied with power from atransformer I3. Triodes II, I2 are controlled by a double switch I4, I5.In the upper po itions I6, IQ of the switch, the control grids of tubesI I, I2 are supplied with a negative bias from D. C. source 22. Thisbias is sufficiently high to block tubes I I, I2 so that no currentflows through electromagnet windings 9, I0.

In the center position I1, of the switch, tube I I remains blocked butthe grid of tube I2 is connected to the center tap 23 of the secondarywinding of transformer I3. A pulsating current of the wave form shown inFig. 3 now flows throu h electromagnet winding III.

In the lower position, IB, 2| of switch I4, I5 tube I2 is blocked by therelatively large negative bias on its control grid. However, tube I I isconductive so that rectified pulsating current flows through winding 9.

Resistors 23, 24, 25 limit current flow through the tube anode circuits.As the contacts of switch I4, I5 only apply potentials to the controlgrid and have little or no current fiow thereacross, contactdeterioration is not a problem. Of course, a suitable relay or relayscould effectively be substituted for switch I 5, iii. If desired, D. C.source 22 can be omitted and grid bias potentials be sup plied fromtransformer l3, with the tubes controlled by phase relations of the gridand plate potentials.

Fig. 5 shows a system employing a Wheatstone bridge and amplifiers asthe control signal circuit. The bridge comprises resistors 26, 2i, astwo arms, and/or potentiometer as the other two arms. Potential isapplied from transformer 3! and a scale St is provided alongpotentiometer 28 whose sliding contact is carried by follower 2 of thedynamic system.

Resistor 26 is the unknown resistance Rx, to be measured, and resistanceEl is the standard resistance Rn- The ratio of the lei t and right armsof potentiometer 2B is given by Ct=R1/R2, where R1 is the left arm. andR2 the right arm. If the bridge is balanced, there is no potentialdifference between points Eli and The value of the unknown resistor isgiven by Rr=Rn.R1/R2=Rn.i, and can be read ofi scale 89 by noting theposi* tion of the sliding contact along the scale.

If the bridge is not balanced, a potential is produced between pointsand having a phase difference of depending upon whether point 29 is tothe right or to the left of the bal point on potentiometer Thispotential is amplified by amplifier and fed to impulse generator Thelatter may be, for example. the arrangement shown 4. Prope ly shapedpulses are selectively fed to electromagnets or depending upon. therelative phase of the bridge output potential, to oscillate rod l. Theparameters of the system are so selected that follower 2 is moved in adir tion to restore bridge balance by movi oint Bil along potentiometer2 3. When balance is effected, the value of resistor 2E3 (RX) can beread from scale 3*]. Capacitors or inductances can be used in the bridgecircuit when it is desired to measure an unknown capacity or inductance.

If the control signal is D. 0., a 13. C. amplifier may be used with thearrangement of Fig. 4. However, such D. C. amplifiers have knowndisadvantages such as high production costs and difficulty ofstabilizing the bias point. Consequently, it is desirable to convert theD. signal into A. C. of a frequency equal. to the oscillation frequencyof rod I, amplify the A. 6., and use the amplified A. C. to directlycontrol the tubes connected to the electroinagnets. A suitable circuitfor effecting this shown in Fig. 6.

The circuit of 6 includes a bridge comprising two resistors and twosubstantially identical dry type rectifiers Bl connectec in polarityopposition. A transformer till supplies to the bridge an A. C. potentialso small that the reotifiers 3! have linear characteristics within thepotential range. In series with rectifier 36 is a capacitor 9! of suchhigh capacity that, with the applied A. C.'potential, the capacitorimpedance is negligible compared with that of the rectifier. A D. C.signal voltage is applied. through terminals ll] and ll, to the points38, 39 on either side of capacitor 91.

When the signal voltage is Zero, there is no potential between bridgeoutput terminals 42, 43. However, when there is an applied signalvoltage, the resistance of one rectifier is increased and that of theother decreased dependent upon the polarity or" the D. C. signalvoltage. As the bridge balance is upset, an output potential appears between points es, and is applied, through capacity to the inpu terminalsat, as of an amplifier ill. The amplified A. C. potential is applied tothe of the electromagnet control tubes.

The phase of the amplified A. 6. potential is dependent upon thepolarity of the 0. signal. As the value of the output A. C. signalcannot be greater than the applied A. C. potential, special precautionsare not necessary to safeguard amplifier ll from overexcitation if theD. signal reaches too high a value.

The arrangement of Fig. 6 can be used with the bridge measurementcircuit of Fig. 5 to control the position of follower 2 on rod i.

Fig. 7 shows the application of the invention to a recording or con misystem. Potentiometer 23 has a D. potential applied thereto from source59 through series resistor c'i which reduces the D. C. potential to sucha value that the potential across the whole potentiometer corre spondsto the maximum value of the (3'. signal voltage. '1 s latter voltage E1is applied to terminals 52, and potentiometer 23 is adjusted until thepotentials at points and 52 are equal.

Should these latter potentials he unequal, the potential difference isapplied to a converter and A. C. amplifier to provide amplified signalfor impulse generator 55, devices it and 55 being supplied from atransformer The impulses from selectively energize electromagnets 5. Sto adjust follower to the balance point which the potentials at 52 areequal. The phase or the impulses is, of course, dependent upon thepolarity of the applied 1). C. potential.

Other known responsive arrangements can be substituted for potentiometer255. Also, if the arrangement of '7 is used with applied A. C. signals,the conversion section oi device 54 may be omitted. By way of example, amovable core or movable coil inductance can be substituted forpotentiometer 28.

Figs. 8 and 9 show the dynamic system as used to effect rotary movementof a follower. In Fig. 8, the oscillating operator comprises a clawstrip 51' surrounding and irictionally cooperable with a rotatable diskfollower Strip 51, preferably of stiff material, is connected to a drawrod 59 mounted on resilient supports so, ill. Rod 59 and strip areoscillated by electromagnets 62, 53. The amount of friction betweenstrip 5? and follower disk is controlled by a clamping screw E i. Asstrip is impulsed rapidly in one direction, it slips over follower 53due to the inertia of the latter. n its slower return movement, strip 57drags follower to rotate in the desired direction.

In the arrangement of Fig. 9, the operator is a jaw til mounted on aradial arm t9 swingable about the rotational axis of follower disk. 58.Jaw G is frictionally cooperable with disk 58. Arm 65 is biased to anintermediate position by springs all, and jaw is oscillated, about theaxis of disk 53, by electromagnets $2,

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application 01" the inventionprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What I claim is:

1. A dynamic system comprising, combination, an oscillatably mountedoperator; resilient restoring means associated with said operator andbiasing the some to a neutral position; relative 1y high inertiafollower in cor. taut value frictional engagement with said operator;and means for applying to said operator relatively sharp impulses tomove the same rapidly in a selected direction against the force of saidrestoring means and relative to follower; said restoring means returningthe narrator to the intermediate position following each impulse and ata relatively slow rate such that the operator frictionally drags thefollower with it during such move ments.

2. A dynamic system comprising, in combination, an oscillatahly mountedoperator; resilient restoring means associated with said operator andbiasing the same to a neutral position; a relatively high inertiafollower in constan value irictional engagement with operator; and meansfor supplying to operator impulses whose frequency is different from thenatural mechanical frequency of the system to move the operator rapidlyin a selected direction against the force of said restoring means andrelative to said follower; said restoring means returning the operatorto the intermediate position following each impulse and at a relativelyslow rate such that the operator frictionall v the follower with itduring such return rnovenre it.

A. dynamic system compirsing, in combination, an oscillatably mountedoperator; resilient restoring means associated with sai and the same toa neutral position; a relai Jely high inertia follower in consta t valueiictional engagement with said ope: for supplying to said operator impireouency differentirorn. the natural mechanical frequency of the saiddynamic n to move the operatcrrapidly in selected o on against the forceof said restoring means and ro e fve to said follower; said restoringmeans retur. the operator to the intermediate position to" ov ing eachimpulse and at a relatively slow rate such that the resulting movementof the follower relative to the operator is in the direction or" theslower movement of the latter.

4. A dynamic system comrising, in combination, an oscillatahly mountedoperator; resilient restoring means associated with said operator andbiasing the same to a neutral position; a relatively high inertiafollower in constant value frictional engagement with said operator; andole,- tromagnetic means for applying to said operator impulses whosefrequency is different from the natural mechanical frequency of the saiddynamic system to move the same rapidly in a selected direction againstthe force of said restoring means and relative to said follower; saidrestoring means returning the operator to the in termediate positionfollowing each impulse and at a relatively slow rate such that theresulting movement of the follower relative to the operator is in thedirection of the slower movement of the latter.

5. A dynamic system comprising, in combination, an oscillatably mountedoperator; resilient restoring means associated with said operator andbiasing the same to a neutral position; a relatively high inertiafollower in constant value frictional engagement with said operator;electromagnetic means operable to oscillate said operator; and means forselectively energizing said electromagnetic means with impulses whosefrequency is different from the natural mechanical frequency of the saiddynamic system to move said operator rapidly in a selected directionagainst the force of said restoring means and relative to said follower;said restoring means returning the operator to intermediate positionfollowing each impulse and at a relatively slow rate such that theresulting movement of the follower relative to the operator is in thedirection of the slower movement of the latter.

6. A dynamic system comprising, in combination, an oscillatablymagnetisable opera-tor; resilient restoring means associated with saidoperator an the same to a neutral position; a relativel high inertiafollower in constant value frict onal engagement with said oporator;BIBCU'GII'IQ? let means operable to oscillate said operator; and meansfor selectively energir. ing said electromagnet means with impulseswhose frequency is different from the natural mechanical frequency ofthe said dynamic system to move said operator rapidly in a selected.direction aga nst the force of said restoring means and rel -ulVQ tofollower; said restoring means returning the operator to theintermediate position following each impulse and at a relatively slowrate such that th resulting movement or the follower relative to theoperator is in the direction of the slower more; ent of the 7. A dynamicsystem as c" d in claim in which said operator comprises a rodosciilatable parallel to its length and said follower is slidahlymounted on said rod.

8. A dynamic system as claimed in claim 3 in which said operatorcomprises rod oscillatahle parallel to its length and said. follower isslidahly mounted on said rod; said restoring means comprising resilientsuspension elements connected to each end of the rod.

9. A dynamic system claimed in claim 5 in which said operator comprisesa rod oscillatable parallel to its length and said follower is slidablvmounted on said rod; said electromagnet means comprising anelectromagnet adjacent each end of the rod.

10. A dynamic system as claimed in claim 6 in which said operatorcomprises a rod oscillatable parallel to its length and said follower isslidably mounted on said rod; said restoring means comprising resilientsuspension elements connected to each end of the rod; and saidelectromagnet means comprising an electromagnet adjacent each end of therod.

11. A dynamic system as claimed in claim 3 in which said operator isoscillatable about an axis and said follower is rotatable about saidoscillation axis.

12. A dynamic system as claimed in claim 3 in which said operatorcomprises a claw oscillatable about an axis and peripherally embracingthe follower which is rotatable about said axis.

13. A dynamic system as claimed in claim 3 in which said operatorcomprises a jaw oscillatable about an axis and peripherally engaging thefollower which is rotatable about said axis.

14. A dynamic system as claimed in claim 6 in which said electromagnetenergizing means cornprises a signal responsive electronic pulsegenerating system; a measuring circuit operable, upon unbalance, totrigger s id electronic system; and a balance restoring arrangementconnected to said follower and included in said measuring circuit.

15. A dynamic system as claimed in claim 6 in which said electromagnetenergizing means comprises a signal responsive electronic pulsegenerating system; a measuring circuit operable, upon unbalance, totrigger said electronic system; a balance restoring arrangementconnected to said follower and included in said measuring circuit; asignal amplifier connected between said measuring circuit and saidelectronic system.

A dynamic system as claimed in claim 6 in which said electromagnetenergizing means comprises a signal responsive electronic pulsegenersystem; and a measuring circuit including a potentiometer andoperable, upon unbalance, to trigger said electronic system; a movablebalancing element of said potentiometer being connected to saidfollower.

KAREL Name Date Holmqvist Feb. 12, 1952 Number

